nca: SparseInfo support (part 1).

Proper CTR IV and context are generated to decrypt the SparseInfo IndirectBucket. More to come at a later time.

include/core/nca.h

@@ -47,6 +47,7 @@ extern "C" {
 #define NCA_IVFC_BLOCK_SIZE(x)                      (1U << (x))
 
 #define NCA_BKTR_MAGIC                              0x424B5452                  /* "BKTR". */
+#define NCA_BKTR_VERSION                            1
 
 #define NCA_FS_SECTOR_SIZE                          0x200
 #define NCA_FS_SECTOR_OFFSET(x)                     ((u64)(x) * NCA_FS_SECTOR_SIZE)
@@ -248,7 +249,7 @@ NXDT_ASSERT(NcaHashData, 0xF8);
 
 typedef struct {
     u32 magic;          ///< "BKTR".
-    u32 version;        ///< offset_count / node_count ?
+    u32 version;        ///< Always NCA_BKTR_VERSION.
     u32 entry_count;
     u8 reserved[0x4];
 } NcaBucketTreeHeader;
@@ -285,7 +286,7 @@ NXDT_ASSERT(NcaAesCtrUpperIv, 0x8);
 
 /// Used in NCAs with sparse storage.
 typedef struct {
-    NcaBucketInfo sparse_bucket;
+    NcaBucketInfo bucket;
     u64 physical_offset;
     u16 generation;
     u8 reserved[0x6];
@@ -293,6 +294,13 @@ typedef struct {
 
 NXDT_ASSERT(NcaSparseInfo, 0x30);
 
+/// Used in NCAs with LZ4-compressed sections.
+typedef struct {
+    NcaBucketInfo bucket;
+} NcaCompressionInfo;
+
+NXDT_ASSERT(NcaCompressionInfo, 0x20);
+
 /// Four NCA FS headers are placed right after the 0x400 byte long NCA header in NCA2 and NCA3.
 /// NCA0 place the FS headers at the start sector from the NcaFsInfo entries.
 typedef struct {
@@ -305,7 +313,8 @@ typedef struct {
     NcaPatchInfo patch_info;
     NcaAesCtrUpperIv aes_ctr_upper_iv;
     NcaSparseInfo sparse_info;
-    u8 reserved_2[0x88];
+    NcaCompressionInfo compression_info;
+    u8 reserved_2[0x68];
 } NcaFsHeader;
 
 NXDT_ASSERT(NcaFsHeader, 0x200);
@@ -336,6 +345,13 @@ typedef struct {
     Aes128CtrContext ctr_ctx;
     Aes128XtsContext xts_decrypt_ctx;
     Aes128XtsContext xts_encrypt_ctx;
+    
+    ///< SparseInfo-related fields.
+    bool has_sparse_layer;
+    u64 sparse_table_offset;            ///< header.sparse_info.physical_offset + header.sparse_info.bucket.offset. Placed here for convenience.
+    u64 sparse_table_size;              ///< header.sparse_info.bucket.size. Placed here for convenience.
+    u8 sparse_ctr[AES_BLOCK_SIZE];
+    Aes128CtrContext sparse_ctr_ctx;
 } NcaFsSectionContext;
 
 typedef enum {
@@ -380,7 +396,7 @@ typedef struct {
     ///< NSP-related fields.
     bool header_written;                                ///< Set to true after the NCA header and the FS section headers have been written to an output dump.
     void *content_type_ctx;                             ///< Pointer to a content type context (e.g. ContentMetaContext, ProgramInfoContext, NacpContext, LegalInfoContext). Set to NULL if unused.
-    bool content_type_ctx_patch;                        ///< Set to true if a NCA patch generated by the content type context is needed and hasn't been completely writen yet.
+    bool content_type_ctx_patch;                        ///< Set to true if a NCA patch generated by the content type context is needed and hasn't been completely written yet.
     u32 content_type_ctx_data_idx;                      ///< Start index for the data generated by the content type context. Used while creating NSPs.
 } NcaContext;
 

source/core/bktr.c

@@ -43,7 +43,9 @@ bool bktrInitializeContext(BktrContext *out, NcaFsSectionContext *base_nca_fs_ct
         update_nca_fs_ctx->section_type != NcaFsSectionType_PatchRomFs || update_nca_fs_ctx->encryption_type != NcaEncryptionType_AesCtrEx || \
         base_nca_ctx->header.program_id != update_nca_ctx->header.program_id || base_nca_ctx->header.content_type != update_nca_ctx->header.content_type || \
         __builtin_bswap32(update_nca_fs_ctx->header.patch_info.indirect_bucket.header.magic) != NCA_BKTR_MAGIC || \
+        update_nca_fs_ctx->header.patch_info.indirect_bucket.header.version != NCA_BKTR_VERSION || \
         __builtin_bswap32(update_nca_fs_ctx->header.patch_info.aes_ctr_ex_bucket.header.magic) != NCA_BKTR_MAGIC || \
+        update_nca_fs_ctx->header.patch_info.aes_ctr_ex_bucket.header.version != NCA_BKTR_VERSION || \
         (update_nca_fs_ctx->header.patch_info.indirect_bucket.offset + update_nca_fs_ctx->header.patch_info.indirect_bucket.size) != update_nca_fs_ctx->header.patch_info.aes_ctr_ex_bucket.offset || \
         (update_nca_fs_ctx->header.patch_info.aes_ctr_ex_bucket.offset + update_nca_fs_ctx->header.patch_info.aes_ctr_ex_bucket.size) != update_nca_fs_ctx->section_size || \
         (base_nca_ctx->rights_id_available && !base_nca_ctx->titlekey_retrieved) || (update_nca_ctx->rights_id_available && !update_nca_ctx->titlekey_retrieved))

source/core/nca.c

@@ -169,10 +169,14 @@ bool ncaInitializeContext(NcaContext *out, u8 storage_id, u8 hfs_partition_type,
         NcaFsSectionContext *fs_ctx = &(out->fs_ctx[i]);
         u8 *fs_header_hash = out->header.fs_header_hash[i].hash;
         
+        NcaSparseInfo *sparse_info = &(fs_ctx->header.sparse_info);
+        NcaBucketInfo *sparse_bucket = &(sparse_info->bucket);
+        
         /* Fill section context. */
         fs_ctx->nca_ctx = out;
         fs_ctx->section_num = i;
         fs_ctx->section_type = NcaFsSectionType_Invalid; /* Placeholder. */
+        fs_ctx->has_sparse_layer = (sparse_info->generation != 0);
         
         /* Don't proceed if this NCA FS section isn't populated. */
         if (!ncaIsFsInfoEntryValid(fs_info)) continue;
@@ -187,9 +191,8 @@ bool ncaInitializeContext(NcaContext *out, u8 storage_id, u8 hfs_partition_type,
         fs_ctx->section_offset = NCA_FS_SECTOR_OFFSET(fs_info->start_sector);
         fs_ctx->section_size = (NCA_FS_SECTOR_OFFSET(fs_info->end_sector) - fs_ctx->section_offset);
         
-        /* Check if we're dealing with an invalid offset/size. */
+        /* Check if we're dealing with an invalid start offset or an empty size. */
-        if (fs_ctx->section_offset < sizeof(NcaHeader) || !fs_ctx->section_size || \
+        if (fs_ctx->section_offset < sizeof(NcaHeader) || !fs_ctx->section_size) continue;
-            (fs_ctx->section_offset + fs_ctx->section_size) > out->content_size) continue;
         
         /* Determine encryption type. */
         fs_ctx->encryption_type = (out->format_version == NcaVersion_Nca0 ? NcaEncryptionType_AesXts : fs_ctx->header.encryption_type);
@@ -229,6 +232,24 @@ bool ncaInitializeContext(NcaContext *out, u8 storage_id, u8 hfs_partition_type,
         /* Check if we're dealing with an invalid section type value. */
         if (fs_ctx->section_type >= NcaFsSectionType_Invalid) continue;
         
+        /* Check if we're dealing with a sparse storage. */
+        if (fs_ctx->has_sparse_layer)
+        {
+            /* Check if the sparse bucket is valid. */
+            u64 raw_storage_offset = sparse_info->physical_offset;
+            u64 raw_storage_size = (sparse_bucket->offset + sparse_bucket->size);
+            
+            if (__builtin_bswap32(sparse_bucket->header.magic) != NCA_BKTR_MAGIC || sparse_bucket->header.version != NCA_BKTR_VERSION || raw_storage_offset < sizeof(NcaHeader) || \
+                !raw_storage_size || ((raw_storage_offset + raw_storage_size) > out->content_size) || !sparse_bucket->header.entry_count) continue;
+            
+            /* Set sparse table properties. */
+            fs_ctx->sparse_table_offset = (sparse_info->physical_offset + sparse_bucket->offset);
+            fs_ctx->sparse_table_size = sparse_bucket->size;
+        } else {
+            /* Check if we're within boundaries. */
+            if ((fs_ctx->section_offset + fs_ctx->section_size) > out->content_size) continue;
+        }
+        
         /* Initialize crypto data. */
         if ((!out->rights_id_available || (out->rights_id_available && out->titlekey_retrieved)) && fs_ctx->encryption_type > NcaEncryptionType_None && \
             fs_ctx->encryption_type <= NcaEncryptionType_AesCtrEx)
@@ -236,11 +257,22 @@ bool ncaInitializeContext(NcaContext *out, u8 storage_id, u8 hfs_partition_type,
             /* Initialize the partial AES counter for this section. */
             aes128CtrInitializePartialCtr(fs_ctx->ctr, fs_ctx->header.aes_ctr_upper_iv.value, fs_ctx->section_offset);
             
+            if (fs_ctx->has_sparse_layer)
+            {
+                /* Initialize the partial AES counter for the sparse info bucket table. */
+                NcaAesCtrUpperIv sparse_upper_iv = {0};
+                memcpy(sparse_upper_iv.value, fs_ctx->header.aes_ctr_upper_iv.value, sizeof(sparse_upper_iv.value));
+                sparse_upper_iv.generation = ((u32)(sparse_info->generation) << 16);
+                
+                aes128CtrInitializePartialCtr(fs_ctx->sparse_ctr, sparse_upper_iv.value, fs_ctx->sparse_table_offset);
+            }
+            
             /* Initialize AES context. */
             if (out->rights_id_available)
             {
                 /* AES-128-CTR is always used for FS crypto in NCAs with a rights ID. */
                 aes128CtrContextCreate(&(fs_ctx->ctr_ctx), out->titlekey, fs_ctx->ctr);
+                if (fs_ctx->has_sparse_layer) aes128CtrContextCreate(&(fs_ctx->sparse_ctr_ctx), out->titlekey, fs_ctx->sparse_ctr);
             } else {
                 if (fs_ctx->encryption_type == NcaEncryptionType_AesXts)
                 {
@@ -252,6 +284,7 @@ bool ncaInitializeContext(NcaContext *out, u8 storage_id, u8 hfs_partition_type,
                 {
                     /* Patch RomFS sections also use the AES-128-CTR key from the decrypted NCA key area, for some reason. */
                     aes128CtrContextCreate(&(fs_ctx->ctr_ctx), out->decrypted_key_area.aes_ctr, fs_ctx->ctr);
+                    if (fs_ctx->has_sparse_layer) aes128CtrContextCreate(&(fs_ctx->sparse_ctr_ctx), out->decrypted_key_area.aes_ctr, fs_ctx->sparse_ctr);
                 } /***else
                 if (fs_ctx->encryption_type == NcaEncryptionType_AesCtr)
                 {